The present application is related to the field of storage system assemblies.
Storage system assemblies are known in which a storage processor is coupled to input/output (I/O) modules by high-speed serial data links, such as serial data links embodying the so-called PCI-Express standard. A PCI-Express link employs one or more single-bit serial lines, individually termed “lanes”, to effect high-rate data transfer between the storage processor and an I/O module. A typical I/O module may provide interconnection to a storage-oriented interconnect bus, such as Fiber Channel or SCSI interconnect buses.
It has been known to mount I/O modules directly to a storage processor module which includes the storage processor, such that the high-speed serial data links are carried directly between the storage processor and the I/O modules by relatively short circuit traces formed on the storage processor module. It has also been known to place the storage processor and the I/O modules on separate modules, and to utilize an intermediate device known as a PCI Express switch on the path between the storage processor and the I/O modules. This arrangement provides for expandability of the I/O interconnect in a system without requiring the addition of storage processor modules. The PCI Express switch examines the addresses of PCI transactions received from a given PCI-Express link and routes the transactions to devices on other PCI-Express links accordingly.